KR20080047449A - Radial seal and method of making - Google Patents

Abstract

A dynamic radial seal includes a rigid casing. The seal also includes an elastomeric casing positioned interior of and bonded to the rigid casing. The elastonieric casing has an axial spring member which extends radially inwardly from and axially along the rigid casing. The axial spring member includes a neck portion which extends from the elastomeric casing and a seal attachment portion that is attached to the neck portion and has a bonding surface. The seal also includes a pre-stressed fluoropolymer seal which has a bonding surface and a sealing surface. A bond joins the bonding surface of the pre-stressed fluoropolymer seal to the bonding surface of the seal attachment portion. The seal attachment portion of the spring member is operative to provide sealing contact of the fluoropolymer seal along the entirety of its sealing surface when engaged with a mating surface of a shaft. The fluoropolymer seal may be formed from PTFE and may include a groove or grooves formed in the sealing surface to enhance the sealing performance of the seal. The elastomeric casing may also incorporate a static seal or temporary dynamic seal to facilitate in-process testing or dirt exclusion, as well as one or more additional dirt exclusion features to protect the fluoropolymer seal from damage caused by environmental contaminants during the use of the seal.

Description

Radial Seal and Method for Making the Same {RADIAL SEAL AND METHOD OF MAKING}

The present invention relates generally to radial seals. More particularly, the present invention relates to an improved fluoropolymer radial seal, such as a radial shaft seal that is directly bonded to the elastomer casing layer.

Radial shaft seals designed for use in sealing vehicle air conditioner compressors, superchargers, power steering pumps, and the main rotating shaft of an engine crankshaft, have a primary sealing element for the fluid or gas to be sealed, such as natural or synthetic rubber. Composite sealing elements designed to be elastomers can be used. In general, the elastomer has sufficient flexibility and elasticity to provide a seal to the shaft. A second stepper, i.e., a lower friction and chemical resistant seal element, is positioned in line behind the elastomeric seal so that an axial gap is provided between the sealing edge of the stripper wear resistant seal and the rear sealing edge of the more elastic elastomeric sealing element. The second sealing element is generally polytetrafluoroethylene (PTFE) or polytetrafluoro, incorporating one or more filler materials to control the mechanical, tribological or various properties of polytetrafluoroethylene (PTFE). It is made from fluoropolymers such as roethylene.

Generally in technology, the elements of such seal structures are typically assembled together and clamped together in a unit using a crimping process. In this process, the rubber element and the PTFE component are crimped between two rigid casings to form the seal. It is common for the PTFE component to also be crimped between the rubber element and either of the rigid casings. It is well known in the art to use flat PTFE washers or preformed conical structures to be joined or clamped to form a seal throughout.

Several radial shaft seal designs are also proposed not to use crimping or clamping of elastomeric and PTFE components in rigid casings, but rather, PTFE sealing elements by forming elastomeric members to both PTFE sealing elements and metal casings. The metal casing which is attached to the temporary metal casing is used. In this design, the PTFE element can only be used as a bearing member to support and control the load of the elastomeric sealing element, so that the sealing function is performed entirely by the elastomeric sealing element. Examples of such seal configurations are disclosed in US Pat. No. 4,274,641 to Cather. In this configuration, the PTFE bearing member and the elastomeric sealing lip join in line and contact with the shaft face. Similarly, several seal designs are disclosed in US Pat. No. 6,428,013 to Johnston et al., Wherein the PTFE sealing element and the elastomeric element are in contact with the shaft face that will be affected by the sealing.

Moreover, other seal designs are also proposed to rest entirely on the PTFE sealing element without incorporating an elastomeric seal ring element to provide a fluid seal. One such radial shaft seal design is disclosed in US Pat. No. 4,650,196 to Bucher et al. In Bucher et al., PTFE elements are bonded to elastomeric casings, which in turn are joined to rigid casings, beyond their length. Similarly, in the literature to Johnston et al, several sealing designs are disclosed that incorporate a PTFE sealing element, such as the first sealing element.

One limitation of the radial shaft design of the related art as described above is that the PTFE sealing element is not sealed along its entire length. For example, in Johnston et al. Design, the PTFE sealing element does not contact the shaft along its entire length. This is also the case for a PTFE member such as Bucher which leads to the use of suboptimal lanes of available PTFE sealing material. Moreover, this radial seal design also provides limited control of the sealing pressure exerted on the shaft or other sealing face by the PTFE sealing element itself, or by a combination of elastomer casing and PTFE sealing element due to the limited contact area of PTFE. Provides limited control of the sealing pressure applied to the other sealing face. In addition to the limitations described above, the radial shaft seal design of the related art also has known limitations relating to the installation of the seal on the shaft or on another member to be sealed. Many known designs where the PTFE lip is the first sealing lip have a free end of the radial sealing lip towards the fluid side, typically the oil side, in the sealed area. This configuration is known to be difficult to install in such as circular shafts, and for assembling the seal on the shaft to avoid damaging the surface of the PTFE material or damaging the surface to compromise the seal. It requires specific assembly measures and methods and the use of specific fixtures and installation tools. Fluoropolymer sealing materials such as PTFE are known to be very susceptible to scratching or other surface damage to sealing surfaces that can effectively seal. In order to enhance the installation capacity of the seal and reduce the tendency to scratch, flip or fold during the installation of the seal, the construction of the inverted PTFE sealing element is proposed as in Johnston et al. The free end faces away from the oil side of the installation. However, such seal configurations are believed to continue to be subject to various limitations as described above.

Therefore, it is desirable to improve the radial shaft seals with PTFE sealing elements that can overcome the limitations of the seal design of the related art.

The present invention relates to a radial seal, such as a radial shaft seal with a fluoropolymer sealing element, in which the elastomer casing is joined to the elastomer casing, which is rigid casing such as a rigid metal casing. The radial seals of the present invention can also incorporate additional features molded into elastomer casings such as dust ejecting lips and static air seals, which can be installed, tested (ie air leak test) or Further enhances operation.

The present invention, in one aspect, relates to a radial seal comprising a rigid casing. The seal also includes an elastomeric casing bonded to the rigid casing and located inside the casing. The elastomeric casing has an axial spring member extending radially inward from the rigid casing and extending along the axial direction of the casing. The axial spring member includes a neck portion extending from the elastomer casing and a seal attachment portion attached to the neck portion and having a joining surface. The seal also includes a pre-stressed fluoropolymer seal having a bonding surface and a sealing surface. The bond connects the bonding surface of the prestressed fluoropolymer seal with the bonding surface of the seal attachment. When the seal attachment portion of the spring member engages with the engagement surface of the shaft, it can be operated to provide a sealing contact of the fluoropolymer seal along the entire sealing surface thereof.

In a second aspect of the invention, the neck portion can be any one of a number of shapes or profiles, including generally linear, curved profiles, bellow profiles, or any of several known shapes or profiles. This provides the advantage of adapting to the various properties of the spring and axial spring members (ie force, flexibility, and followability), including the attachment and neck of the elastomer casing.

In a third aspect of the invention, in order to apply a generally constant sealing pressure to the fluoropolymer seal element, a sealing pressure that may be substantially constant or may vary in the axial and radial directions along the axial length of the fluoropolymer seal element. The thickness of the attachment portion of the axial spring member may vary in the axial direction to provide.

In a fourth aspect of the invention, the fluoropolymer sealing element is additionally integrated with several sealing features at the bonding surface of the fluoropolymer element, the fluoropolymer element comprising a threaded or several continuous groove pattern, or One or more circumferential grooves or channels, or other discontinuous groove patterns, or combinations thereof. These groove patterns may be constant or vary in depth along the length of the fluoropolymer element. The grooves also consist of alternately raised ribs. These grooves offer the advantage of reinforcing the retention of a fluid, such as oil to be sealed, by actuating the radial seal, ie by providing hydrodynamic pumping of the fluid associated with rotation of the sealing surface.

In a fifth aspect of the invention, the radial seal additionally comprises an air lip or seal from the air side of the radial seal to the elastomer casing. Such a seal is preferably a static seal, but temporarily or momentarily during a limited period of time, such as initial process or in-process testing, during the manufacture of a device incorporating a radial seal and / or during use of the device. ) May be used in connection with the seal. In the context of an internal combustion engine, this offers the advantage of in-process pressure testing of the engine during the manufacturing and assembly process of the engine, which is temporary or in-plane on the shaft face to be sealed by a radial seal to facilitate the testing. There is no need to provide a process seal, which facilitates the adoption or disposal of the engine.

In a sixth aspect of the invention, the radial seal discharges one or more integral dusts into the elastomer casing on the air side of the seal, in order to expel dust and other contaminants from the fluoropolymer seal element during use of the installed device. Lips can be additionally integrated.

In a seventh aspect of the invention, the prestressed fluoropolymer element generally has a stress profile that varies in length along the length of the fluoropolymer element. Advantageously, such a stress profile can be made by controlling the thickness of the element and / or the thickness profile of the element, depending on the amount of prestress that the PTFE element receives after stretching the PTFE element to its final position in the mold. Moreover, the method of stretching the fluoropolymer element is based on how the elongated seal is loaded into the mold along with the other elements of the radial seal, with the element having a stress profile in two directions (one direction the other direction). In the opposite direction).

In an eighth aspect of the invention, the radial seal of the invention may be constructed in a basic configuration or in an upside down configuration. In either of these configurations, the radial seal of the present invention is known to be less susceptible to potential seal damage issues associated with the installation of the seal on the shaft or other side to be sealed. Indeed, the configuration of the radial seal of the present invention is basically due to the fact that it has two free ends and thus has less difference as to whether the seal is installed first from the free end than the seal design of the related art. It reduces the difference between the conventional installation configuration and the installation configuration that is upside down. This better represents the configuration lying in both directions. Moreover, this feature may include the ability to direct the prestress level in the fluoropolymer element such that the highest level of prestress and thus the maximum sealing force is applied to a surface closer to the installation end of the seal or to a surface to be sealed away from the end. All. For example, the fluoropolymer element is located in a seal with a prestress level profile directed such that the sealing force applied to the sealing face is lowered closer to the installation end to improve the installation of the seal.

In a ninth aspect of the invention, a new method for making radial seals comprises: an inner diameter using a mandrel device and at least an outer diameter relative to the inner diameter to form a prestressed fluoropolymer seal having an inner diameter and an outer diameter; Elongating the fluoropolymer seal preform; Positioning a prestressed fluoropolymer seal having a bonding surface and a sealing surface in a mold having a mold cavity, wherein the bonding surface is exposed to the mold cavity; Positioning a rigid casing in a mold cavity near the prestressed fluoropolymer seal; And an axial spring member extending axially and radially inwardly from the casing, the elastomeric material being formed to form an elastomeric casing bonded to the rigid casing and positioned inside the casing. Inserting into a mold cavity, wherein the axial spring member includes a neck portion extending from the elastomer casing and a seal attachment portion attached to the neck portion and having a bonding surface, wherein the neck portion is formed of a prestressed fluoropolymer seal. A bond connecting the bonding surface to the bonding surface of the seal attachment, the seal attachment being operated to provide sealing contact of the fluoropolymer seal along the entire sealing surface when engaged with the engagement surface of the shaft.

1 is a cross sectional view of a first embodiment of a radial shaft seal of the present invention;

2 is a cross sectional view of a second embodiment of a radial shaft seal of the present invention;

3 is a cross sectional view of a third embodiment of a radial shaft seal of the present invention;

4 is a cross sectional view of a fourth embodiment of a radial shaft seal of the present invention;

5 is a cross sectional view of a fifth embodiment of a radial shaft seal of the present invention;

6 is a cross sectional view of a sixth embodiment of a radial shaft seal of the present invention;

7 is a cross-sectional view of the radial shaft seal of the present invention in sealing contact with the radial shaft;

8 is a cross-sectional view of a mandrel loaded on a mold core used to prestress the fluoropolymer seal prior to bonding the fluoropolymer seal to the elastomer casing and installation tool, in order to stretch the fluoropolymer seal over the mandrel and onto the mold core. ;

9A is an enlarged cross-sectional view of zone 9 of the mandrel of FIG. 8 during stretching of the fluoropolymer seal on the mandrel by operation of an installation tool showing a first seal position in the mold,

9B is an enlarged cross-sectional view of zone 9 of the mandrel of FIG. 8 during stretching of the fluoropolymer seal on the mandrel by operation of an installation tool showing a second seal position in the mold,

10 is an enlarged cross-sectional view of a fluoropolymer seal located on a mold core and adjacent to a rigid casing within a mold used to form the radial shaft seal of the present invention;

FIG. 11 is an enlarged cross-sectional view of Zone 11 of FIG. 10, prior to filling the mold with elastomeric material;

12 is an enlarged cross-sectional view of the zone 11 of the mold of FIG. 10 after filling the mold with an elastomeric material; And

13 is a cross-sectional view of the molded seal of the present invention before trimming the molded seal (shown with dashed lines) and after trimming.

The present invention relates to radial shaft seals for sealing passages of fluid in relation to rotating radial shafts. The radial casing is provided with an elastomeric casing in the rigid casing and a first sealing member in which the prestressed fluoropolymer seal is attached in this order to the elastomer casing. In general use, the prestressed fluoropolymer seal is in fluid tight sealing with the sealing surface of the radial shaft. Radial shaft seals are suitable for many radially rotating shaft sealing applications, in particular for many automotive applications, for sealing fluid passageways including crankshaft seals. Although not shown, it can be seen that the invention is equally applicable to a seal using a wear sleeve element, wherein the wear sleeve element is located on a circular shaft.

1-6 illustrate several embodiments of radial shaft seals 10 according to the present invention, which are molded and trimmed, wherein the seal is from a forming press to provide a finished or partially finished seal. Molded in a suitable device, such as a removed and trimmed injection molding press. The seal 10 can be made using any one of a number of known methods, which method provides rigidity of prestressed fluoropolymer seals using an elastomeric member or casing interposed to form the seal 10. In order to connect to the casing, compression, transfer, or injection molding, or a combination thereof, or similar processes are included.

1-6, the radial shaft seal 10 comprises a rigid casing 12 having an outer surface 14 and an inner surface 16. The seal 10 is also located in a rigid casing and preferably at least partially located in the inner surface 16 and at least partially bonded to the inner surface 16, preferably bonded to the rigid casing 12. Elastomer casing 18 is included. The elastomer casing 18 may also be partially located and bonded to the outer surface 14. Elastomer casing 18 may also be used to provide a static seal to the fluid to be sealed in connection with the device containing the shaft, for which a fluoropolymer seal element is used as the dynamic sealing element. The elastomeric casing 18 has an axial spring member 20, which spring member is radially inward and axially from the rigid casing 12, in particular the inner surface of the rigid casing 12. Extends axially and radially inward away from the inner surface along 16). However, depending on the shape of the rigid casing 12 and the shape and direction of the axial spring member 20, the axial spring member 20 may also be bent radially inward, for example. It extends axially along the outer surface 14 and radially away from the outer surface as having a j-shaped shape. The axial spring member 20 has a neck 22 extending from the elastomer casing 18 on the other end 26 opposite the one end 24 to the seal attachment 28 with the joint surface 30. Doing. The seal attachment 28 generally includes a reminder of the axial spring member 20 rather than the neck portion 22. The seal 10 also includes a prestressed, slippery, low modulus friction fluoropolymer seal 32, which has an outer or abutment surface 34 and an inner or sealing surface 36. The axial spring member 20 extends axially along the longitudinal axis 40 of the radial seal 10 and applies a spring force to press the spring member 20 and the fluoropolymer seal against the surface to be sealed. Add. The radial neck portion 22 has a generally linear or curved profile (FIGS. 1 and 2) formed with a truncated conical radial element, and a convoluted profile (FIGS. 3 and 4) formed with a conical truncated conical radial element. ), One of the shape and section profile of a number of neck portions, such as wavy or wavy profiles (FIGS. 4 and 5) forming converging bellow-shaped radial elements, and various other neck portion shapes and section profiles. have. The neck portion 22 is associated with the longitudinal axis of the seal and the longitudinal axis of the shaft, or the radial seal 10 may accommodate some misalignment to the dynamic eccentricity or runout of the shaft when the shaft rotates. To be able. This is a significant advantage as an advantage of the present invention over conventional seal designs. At the opposite end 26 of the neck portion 22, the axial spring member 20 also includes an attached axially extending attachment 28. Attachment 28 extends along the entire length of fluoropolymer seal 32. 3 and 4, the section thickness t of the attachment portion 28 is shown generally constant along its length, except where it is connected with the neck portion 22. This allows attachment 28 to provide a generally constant sealing pressure to fluoropolymer seal 32 when a radial seal is installed on the shaft. It is known to fit the attachment 28 for several cases of radial seal 10 with a thickness range of approximately 0.010-0.060 inches. However, as shown in FIGS. 2, 5 and 6, the thickness of the attachment portion 28 also results from the fact that the sealing pressure provided as part of the spring member 20 varies similarly along its length with the thickness of the profile. As can be changed along the length of the attachment portion. The thickness can vary depending on several suitable profiles. 2, 5 and 6, the profile thickness varies linearly from the maximum thickness t2 to the minimum thickness t1. The profile thickness may vary linearly as shown or may have an involute, convolut or other curved profile. The section thickness profile will of course change the spring properties of the spring member 20, and the spring compression force resulting in the seal 10 and the prestressed fluoropolymer seal 32 is interfitted as described in more detail herein. On the furnace shaft 38.

The prestressed fluoropolymer seal 32 is preferably molded from polytetrafluoroethylene (PTFE). As best known in the art, fluoropolymers such as PTFE used in fluoropolymer seals 32 may be included in various fillers or other materials used to modify the mechanical, tribological or other properties of the fluoropolymer. have. The prestressed state of the fluoropolymer seal 32 is such that the fluoropolymer preform 72, in order to create a sufficient sum of residual internal stresses, such as plastic deformation of the preform 72 and prestress in the fluoropolymer seal 32. 8) Preferably made by stretching a PTFE washer or hollow disk. The prestress size and prestress profile along the length of the seal can be affected and can vary as described in more detail herein. The seal 10 also has a joint interfitting portion 33 which joins the outer or bonding surface 34 of the prestressed and low modulus friction fluoropolymer seal 32 with the bonding surface 30 of the seal attachment 28. Include. The seal attachment 28 is a frictional fluoropolymer seal such as a polytetrafluoroethylene seal prestressed along the entire sealing face 36 when the seal is engaged with the engagement shaft 38 or other face to be affected. 32) prestressed, slippery, and operated to provide a low rate of sealing contact. The fluoropolymer seal 32 may engage the sealing surface 36 with a groove 60, such as a continuous spiral, helical or threaded groove, with the groove preferably inclined to the fluid or oil side of the seal. have. Such grooves or patterns of grooves are well known and operate hydrodynamic pumping according to the relative rotation of the radial seal 10 and the sealing surface. The depth of the groove 60, or the plurality of grooves 60, may be constant along its length, or may vary in depth from one end of the fluoropolymer seal to the other end. Continuous grooves 60 are also included together or separately with one or more discontinuous circumferential grooves or channels (not shown) that are well known and used to stop or accumulate fluid to be sealed during radial seal 10 operation. . Whether the groove 60 is continuous, discontinuous or combined, it can be formed using very well known molding methods such as coining or machining. Grooves 60, continuous or discontinuous, or a combination thereof, may be molded using known molding methods such as coining or machining. The groove 60 may optionally consist of raised ribs formed in the sealing surface 36. The fluoropolymer seal 32 is intermediately bonded to the attachment portion 28 of the elastomer casing 18 by conventional means, such as by connecting the elastomer directly by injection molding onto the outer surface of the prestressed fluoropolymer seal 32. It is preferable to be chemically bonded at the joining intermediate fitting portion 33 to the portion 30. It is well known how to form elastomeric casings and affect the chemical bonding of the fluoropolymer seal 32 and the attachment 28.

Rigid casing 12, elastomeric casing 18 and prestressed fluoropolymer seal 32, as well as various elements of radial seal 10, are directed radially about the longitudinal axis of seal 10. When the radial seal 10 is installed on the shaft 38, the longitudinal axis 40 of the radial seal 10 preferably coincides with the longitudinal axis of the shaft 38. However, due to manufacturing tolerance tolerances, it is known that some misalignment, offset of one axis, nonparallel, or a combination thereof occurs. Thus, the radial seal 10 is selected in relation to the shaft 38 and made to a particular dimension, so that the shaft sealing surface 46 of the shaft 38 and the sealing surface 36 of the prestressed fluoropolymer seal 32 are thus made. It is preferred that there is an intermediate fit along the entire length of the sealing surface 36. To achieve this, the shaft 38 is provided with a chamfer 42 or bevel or similar lead-in edge 48 to enhance engagement and installation of the radial seal 10 on the shaft 38. ) Is typically coupled at the free end or at the installation end. A part of the chamfer 42 and the lead-in edge 48 of the free end or installation end of the shaft 38 has an intermediate fit in the radius of the installation end 44 of the radial seal 10, while the chamfer ( The incremental radius of the chamfer 42 is generally chosen such that the radius at the opposite end 50 of the 42 is such that the intermediate fit described above with respect to the shaft 38 and the radial seal 10 takes place.

Generally, an intermediate fit is designed to occur anywhere along the length of the chamfer 44. As is well known in conventional seal designs for seals incorporating a fluoropolymer seal element such as PTFE, the fluoropolymer seal 32 applies a predetermined sealing pressure at the sealing face 36 to the sealing face 46 of the shaft 38. ), The degree of interfit is chosen. As shown in FIGS. 1-6, the radial seal 10 is mounted to the shaft 38 by moving the radial seal 10 in the direction of arrow 52 or by moving the shaft 38 in the opposite direction. Thus, the total adhesive face 36 is in sealing contact with the sealing face 46. This full contact of the total sealing face 36 of the fluoropolymer sealing element 32 along the sealing face 46 of the shaft 38 is an important feature of the present invention and has significant and advantages over the related art in seal design. Indicates an improvement. The embodiment of the invention shown in FIG. 1 shows that the free end and the installation end 44 of the seal are far from the air side 100 of the seal and closest to the oil side, more specifically the fluid side 200 of the seal. In the sense that it is positioned to represent a conventional radial seal 10 alignment. When the radial seal 10 is assembled to the shaft 38, the zone indicated by reference numeral 200 is an enclosed, sealed zone and is referred to as the oil side, while the zone indicated by reference numeral 100 is outside the sealed zone. It is cited as the air side.

The rigid casing 12 is shown in various shapes in FIGS. 1-6 and is required for overall use in the radial seal 10 and has any suitable shape depending on the desired shape of the other seal element. The rigid casing 12 is preferably a metal casing and may be molded from any suitable metal, such as steel. Rigid casing 12 may be molded from a suitable rigid engineering plastic or plastic composite. Rigid casing 12 generally includes an axial case portion 13 and a radial case portion 15. The elastomeric casing may be bonded to either or both of the axial casing portion 13 and the radial casing portion 15.

Elastomer casing 18 is virtually any elastomer, including fluoroelastomers, polyacrylates, nitriles, hydrogenated nitriles or silicone or similar thermoset elastomers, or thermoset polymer elastomers such as suitable thermoplastic elastomers. Can be. The elastomeric material of the elastomeric casing 18 may include the operating temperature of the seal, the chemical or compatibility with respect to the fluid to be sealed, the bonding and other compatibility with the material of the rigid casing 18 and the fluoropolymer seal element 32, and It can usually be chosen in relation to usage requirements such as other factors. The elastomeric casing 18 may be bonded to and attached to at least one of the outer surface 14 and the inner surface 16 of the casing, and may be bonded according to the design of the seal. The position of the elastomeric casing 18 of the rigid casing 12 will be determined in relation to the static sealing requirements associated with the elastomeric casing 18 as described above and as is well known in the art. 1-6, the static sealing portion 54 of the radial seal 10 is molded by joining a portion of the elastomeric casing 18 to the outer surface 14 of the rigid casing 12. 2, a radius, comprising one or more elastomeric static sealing lips 56, as well as one or more elastomeric discharge lips 58, for discharging dust or other contaminants from one zone with respect to the fluoropolymer seal 32 Other features of the directional seal 10 may be additionally integrated. The elastomeric sealing lip 56 is located at the air side 100 of the radial seal 10 and the prestressed fluoropolymer seal 32 and provides no sealing pressure or provides minimal sealing pressure on the shaft 38. In order to achieve this, it is particularly desirable to be designed and dimensioned so as not to interfere with the dynamic sealing operation of the prestressed fluoropolymer seal 32. The sealing lip 56 undergoes in-process pressurization and air leak testing (ie, from the oil side 200) during assembly of a device incorporating a radial seal 10 such as an internal combustion engine. It is generally used as a static seal to facilitate it. Sealing lip 56 may also act as a dynamic seal temporarily when the lip is in contact with the shaft, but because it is located on the air side of the seal and is typically not exposed to lubricants such as oil, It is worn out rapidly by the rotation of the shaft. The sealing lip 56 also acts as a first dust ejecting lip 58 which is operative to eject dust from an external source at a portion of the shaft 38 near the prestressed seal 32. Sealing lip 56 may also be designed to not apply sealing pressure to the shaft except when the radial seal is pressurized from air side 100, such as when responding according to pressure tests associated with the device. From the prestressed fluoropolymer seal 32, a discharge lip 58 is positioned and formed to operate to discharge contaminants such as dust. Another discharge lip may be integrated as shown in FIGS. 2 and 13. The ability to integrate the sealing lip 56 and the exit lip 58 without adversely affecting the dynamic sealing properties of the prestressed fluoropolymer seal 32 is one of the important advantages of the present invention.

3 shows another embodiment of the present invention. Referring to FIG. 3, the radial seal 10 is closer to the air side 100 of the radial seal 10 with the free end of the fluoropolymer seal 32 having a convoluted neck 22. It is a configuration that is upside down in terms of facing the air side.

4 shows another embodiment of the present invention. The radial seal of FIG. 4 indicates that the radial seal 10 of FIG. 4 includes an elastomeric sealing lip 56 to provide a static air seal to the air side 100 of the seal 10 as described above. Except for the seal of FIG. The seal of FIG. 4 may additionally also include one or more additional ejection lips 58 (not shown) attached to the free end of the attachment portion 28.

5 illustrates another embodiment of the present invention. 5, the radial seal 10 has a free end portion of the fluoropolymer seal 32 that is closer to the oil side of the radial seal 10 with a bellows shaped neck portion 22 and with the oil side. In terms of facing, a conventional laydown configuration is taken. This embodiment also exhibits a thickness that varies along the length of the attachment 28.

6 shows another embodiment of the present invention. 6, except that the radial seal 10 of FIG. 6 includes an elastomeric sealing lip 56 to provide a static seal on the air side of the seal as described above. Same as the seal. The static seal 56 also acts as a dust ejecting lip 58. Such a seal configuration may also incorporate one or more additional discharge lips 58 (not shown) as described above.

7 shows a radial seal 10 of the present invention mounted on a radial shaft 38. The total length of the sealing surface 36 is operated to seal the oil on the oil side 200 leaking to the air side 100 in sealing contact with the oil. The helical groove 60 is operated to pump oil which moves toward the air side 100 and the free end 44 behind the oil side 200 in accordance with the relative rotation of the radial seal 10 and the shaft 38.

8-12, a method 300 for manufacturing or making a radial shaft seal 10 according to one aspect of the present invention is disclosed, which method comprises: a prestressed fluoropolymer having an inner diameter and an outer diameter; Elongating 310 a fluoropolymer seal preform 72 having an inner diameter 62 using a mandrel device 64 and at least an outer diameter 74 to the inner diameter 62 to mold the seal 32. ); Positioning (320) a prestressed fluoropolymer seal (32) having a bonding surface (34) and a sealing surface (36) in a mold (66) having a mold cavity (70). Exposed to this mold cavity 70; Positioning 330 the rigid casing 12 in the mold cavity 70 proximate the prestressed fluoropolymer seal 32; And an axial spring extending axially along the rigid casing 12 and radially inward from the casing to form an elastomeric casing 18 bonded to and located within the rigid casing 12. Directing the elastomeric material into the mold cavity (70) to have a member (20); wherein the axial spring member (20) comprises a neck (22) extending from the elastomer casing (18) and It consists of a seal attachment portion 28 attached to the neck portion 22 and having a bonding surface 30, which bonds the bonding surface 34 of the prestressed fluoropolymer seal 32 to the seal attachment portion 28. A bond 33 joining the joining face 30 of the seal face, wherein the seal attachment portion 28, when engaged with the mating face 46 of the shaft 38, prestressed fluorine along the entire sealing face 36; In sealing contact with the polymer seal 32 It works. The method 300 uses a similar method of forming the prestressed fluoropolymer seal 32 as disclosed in U.S. Patent Application No. 10 / 366,253 (Representative File No. 71024-211) of February 13, 2003, The patent document is referred to throughout this specification. The seal of the patent application differs from the seal of the present invention in that the elastomeric element of the seal consists of a portion of the dynamic radial seal and the fluoropolymer sealing element does not seal along the entire length of the fluoropolymer element. The method of stretching and prestressing the fluoropolymer element is similar to the aspect of method 300 above.

The prestressed fluoropolymer seal 32 is initially unstressed or elongated with a fluoropolymer seal preform 72, such as a flat cylindrical fluoropolymer washer 72. The washer preferably has a thickness in the range of approximately 0.010 to 0.060 inches. The outer diameter portion 74 and the inner diameter portion 62 are selected such that half of these differences determine the length of the second or sealing surface 36 of the radial seal 10. 8, 9A and 9B, a flat fluoropolymer washer 72 lies on top 76 of the mandrel. The diameter of the upper end 76 of the mandrel 64 is smaller than the inner diameter 62 of the fluoropolymer washer 72. The inflatable pusher or installation tool 78 is in the form of a plunger having an inflatable lower section, such as a plurality of separate inflatable fingers 80. As the installation tool moves in contact with the mandrel 64 and the flat washer 72 in the direction shown by arrow 84, the expandable finger portions 80 are each used to engage the flat washer 72. It is provided. As shown in FIGS. 9A and 9B, the finger 80 of the inflatable pusher or installation tool 78 moves along the tapered outer surface 86 of the mandrel 64, thus expanding the inflatable finger 80. The contact surface 82 of the < RTI ID = 0.0 >) < / RTI > The mandrel 64 has one or more tapers and is formed such that the diameter of the lower surface 87 of the mandrel 64 is at least larger than the inner diameter 62 of the washer of the fluoropolymer. The taper is shown to have a linear profile, but may also have a convolutional or involute profile. For example, the size of the preform 72, together with the size of the post face, the mandrel 64 and the associated portions of the mold 66, is shared by the amount of elongation performed on the fluoropolymer seal preform 72 and the prestressed fluoropolymer seal 32. The amount of prestress used is determined. The washer 72 and the mandrel 64 are selected such that the diameter of the lower surface 87 of the mandrel 64 is greater than the outer diameter of the fluoropolymer seal preform 72. Therefore, the washer 72 is reliably prestressed to both the inner diameter portion 62 and the outer diameter portion 74. As the washer 72 slides below the outer surface 86 of the mandrel 64, it is plastically stretched or deformed to prestress the washer. The level of stress along the length of the prestressed fluoropolymer seal 32 is such that a portion of the washer 72 adjacent to the inner diameter 62 of the fluoropolymer washer 72 is stretched to a greater extent than the portion adjacent to the outer diameter 74. Can change. The inner diameter 62 of the washer 72 is preferably such that the inner diameter 62 of the fluoropolymer seal 32 and the prestressed first end 90 are expanded by lowering the plunger 78 along the mandrel 64. Elongated conical as shown in FIG. 9A or 9B. The outer diameter portion 74 also expands as it slides down along the mandrel, prestressing the second end 92 of the fluoropolymer seal 32. In the embodiment shown in FIG. 9A, the amount of internal stress at the first end 90 is greater than the amount of internal stress at the second end 92 because deformation occurs more. In the stretching step 310, the fluoropolymer washer 72 is stretched to mold the prestressed seal 32. Washer 72 is elongated to approximately 5 to 180 percent of the minimum size of the inner diameter to represent a predetermined amount of prestress on the seal 32, and more specifically within the range of approximately 5 to 120 percent of the initial size of the inner diameter. Elongate. The prestressed fluoropolymer seal 32 remains stretched and prestressed before being molded with the elastomeric material and does not go through any one step to relieve internal stresses such as various ways of annealing or removing stresses. .

The method 300 proceeds to placing 320 the prestressed fluoropolymer seal 32 in the mold 66 to engage the post face 66 of the mold 66. In FIG. 9A, the second end 92 of the prestressed fluoropolymer seal 32 is placed on the first showr 94 before the first end 90 and the prestressed seal 32 are in the direction shown. Pass through. Optionally, in FIG. 9B, the second end 92 causes the first show rater 94 by rolling the second end upward over the finger portion while the first end 90 is pressed on the first show rater 94. By carefully adjusting the seal as the seal slides on the first show rater 94, as shown in FIG. 2, the second end 92 and the prestressed fluoropolymer seal 32 are shown. The first end 90 of the currently prestressed fluoropolymer seal 32 passes over the first showr 94 before it ends in the alternating direction. Mandrel 64 and first show rater 94 may be configured to facilitate positioning of first end 90 and second end 92. The ability to change the orientation is particularly advantageous, which allows the prestressed seal to be directed to a higher level of prestress in opposite directions using the same mold, thus making up the prestressed fluoropolymer seal 32 without changing the mold. This is because molding is possible in at least two embodiments.

Following the step 320 of positioning the prestressed fluoropolymer seal, the seal 32 is preferably placed in the mold 66, bonded to the post face 68, and placed in the second showr 96. As shown in FIG. 8, it can be seen that the mandrel 64 may consist of a portion (not shown) of the central element 96 of the mold 66, or may consist of a separate (and removable) element. 8, 9A and 9B as if the post face 68 has a taper extending slightly down, the post face has a first end diameter 69 and a second end diameter 71. FIG. And the second end diameter portion is larger than the first end diameter portion. Optionally, the post face is provided with a taper (not shown) extending upwards such that the first end diameter 69 is located below the second end diameter 71 and the second end diameter is greater than the first end diameter. Even bigger. The prestressed seal 32 can be positioned on the post face in any of the configurations described above. Where the post face is tapered, it is contemplated that the post face 68 may have a linear taper, as shown in FIGS. 9A and 9B, or may have an involute or convolut taper. Optionally, the post face may be a straight profile (not shown) that is approximately parallel to the longitudinal axis 67 of the mold 66, or a concave, convex or multiple curved profile, or a bellows or composite profile. It is believed that multiple composite profiles can be provided.

Before or after the stretched fluoropolymer seal is placed in the mold, the method 300 includes a step 330 of positioning the rigid casing 12 in the mold 66. One or more interlocking mold elements (such as elements 98, 102, 104, 106, 108) are particularly suitable for molding elements 98, 102, 104, 106 and 108 for molding mold cavity 70. It is preferable to have one or more positioning features, such as show rate 110, to position the rigid casing 12 in the mold 66 while moving in place.

After the rigid casing 12 is positioned in the mold 66, as shown in FIG. 12, the method 300 may use any of several known molding techniques to form the elastomeric material in a mold cavity ( Proceed to step 70). The elastomeric material is selected using known criteria for compatibility with rigid casing, prestressed fluoropolymer seal 32, and radial seal 10 with the intended use environment. Suitable elastomeric material may be directed to the mold cavity 70 and may be cured at elevated temperatures and / or pressures typically for forming the integral radial seal 10 with the elastomer casing 18 of the present invention. . After molding, there may additionally be another post curing operation.

In order to maintain the fluoropolymer seal 32 in the prestressed or elongated state, in the prior art design, in addition to radially using less fluoropolymer than the second rigid casing 12 typically used for crimped seal designs. A shaft seal is provided to allow for significant savings.

Referring to FIG. 13, the radial seal 10 'of the present invention is shown in dashed-dotted line, which represents an as-molded condition. After being typically extracted from the mold 66, the radial seal is trimmed to form the finished radial seal 10 shape shown as an embodiment in FIG. 13 and to remove molding flashing. Trimming may be performed by cutting, shearing or otherwise removing the seal from the flashing using a tool to remove or trim the flashing from the as-molded seal 10 '. Optionally, the molded seal 10 'may be adapted to provide a thinned section (not shown) at location 120, tearing the flashing without requiring cutting or other removal tools at that location. ) To remove flashing by ripping.

Claims (50)

Rigid casing; An elastomer casing positioned and bonded within the rigid casing, the elastomer casing having an axial spring member extending radially inward from the rigid casing and extending axially along the casing; Prestressed fluoropolymer seals with bonding and sealing surfaces; And A bond for connecting the bonding surface of the prestressed fluoropolymer seal with the bonding surface of the seal attachment portion; The axial spring member includes a neck portion extending from the elastomer casing and a seal attachment portion attached to the neck portion and having a bonding surface, And the seal attachment is operable to seal the fluoropolymer seal along the entire sealing face when in engagement with the engagement face of the shaft. The radial seal of claim 1 wherein the rigid casing is made of metal. The radial seal of claim 1 wherein the metal is made of steel. 2. The radial seal of claim 1, wherein the rigid casing is made of rigid plastic or rigid plastic polymer. 2. The radial seal of claim 1, wherein the rigid casing comprises a radial portion and an axial portion. 6. The radial seal of claim 5 wherein the casing of the elastomer is joined with the rigid casing along at least an inner surface of the radial portion. 6. The radial seal of claim 5 wherein the casing of the elastomer is joined to the rigid casing along at least an outer surface of the radial portion. The radial seal of claim 1 wherein said prestressed fluoropolymer seal comprises polytetrafluoroethylene. 2. The radial seal of claim 1, wherein the prestressed fluoropolymer seal has a sealing groove formed in the sealing surface. 10. The method of claim 9, wherein the sealing groove is a series of grooves extending radially with respect to the sealing surface and extending axially along the sealing surface, wherein the sealing groove is at least one of a series of grooves and / or circumferential grooves. Radial seal made with. 11. The radial seal of claim 10, wherein the depth of the sealing groove varies axially along the sealing surface. 9. The radial seal of claim 8, wherein the sealing groove is a circumferential groove. The radial seal of claim 1 wherein said prestressed fluoropolymer seal comprises a plurality of sealing grooves formed in said sealing surface. The radial seal of claim 1 wherein said neck portion has a substantially linear profile. The radial seal of claim 1 wherein said neck portion has a substantially curved profile. The radial seal of claim 1, wherein the neck portion has a substantially convoluted profile. The radial seal of claim 1, wherein the neck portion has a substantially bellow-shaped profile. The radial seal of claim 1 wherein said prestressed fluoropolymer seal is prestressed by radially stretching a fluoropolymer washer having an inner diameter in the range of approximately 5-180% of the inner diameter. The radial seal of claim 1 wherein the prestressed fluoropolymer seal has an internal stress that changes axially along the sealing surface. 10. The seal attachment of claim 1 wherein the seal attachment and the prestressed fluoropolymer seal are operated to provide an interfit of the sealing face at the engagement shaft, the attachment engaging the engagement shaft by applying a radial compressive force at the shaft. And radially seal to provide sealing contact of the fluoropolymer seal along the entirety of the sealing face. 2. The method of claim 1 wherein the prestressed fluoropolymer seal has a thickness and the seal attachment portion also has a thickness, wherein the thickness of the attachment portion is one quarter greater than the thickness of the prestressed fluoropolymer seal. Characterized by radial seal. 2. The radial seal of claim 1, wherein the thickness of the prestressed fluoropolymer seal thickness is in the range of approximately 0.010-0.060 inches. 2. The radial seal of claim 1, wherein the seal attachment has a substantially same thickness on the bonding surface of the prestressed fluoropolymer seal. The radial seal of claim 1, wherein the seal attachment portion has a thickness that changes axially on the joint surface of the prestressed fluoropolymer seal. 2. The radial seal of claim 1, wherein the attachment portion has a thickness that changes radially about the joining surface of the prestressed fluoropolymer seal. 2. The radial seal of claim 1 wherein the casing of the elastomer further comprises a sealing lip operable to provide a static sealing contact with the mating face of the shaft in accordance with the axial force applied to the sealing lip. 2. The casing of claim 1, wherein the casing of the elastomer further comprises a radially inwardly extending and axially extending outlet operable to expel foreign matter from the sealing surface of the shaft and the prestressed fluoropolymer seal. Radial seal made. The radial seal of claim 1 wherein the casing of elastomer comprises at least one thin section that is operative to provide a tear line for molding flashing removal. A method of making a radial shaft seal, Stretching the fluoropolymer seal preform having an inner diameter portion and at least an outer diameter portion to the inner diameter portion using a mandrel device to form a prestressed fluoropolymer seal having an inner diameter portion and an outer diameter portion; In a mold having a mold cavity, positioning a prestressed fluoropolymer seal having a bonding surface and a sealing surface exposed to the mold cavity; Positioning a rigid casing in a mold cavity proximate the prestressed fluoropolymer seal; And Elastomeric material is formed to form an elastomeric casing having an axial spring member located inside the rigid casing and bonded to the casing and extending radially inwardly from and along the casing. Leading to the mold cavity; The axial spring member includes a neck portion extending from the elastomer casing and a seal attachment portion attached to the neck portion and having a bonding surface, the neck portion for connecting the bonding surface of the prestressed fluoropolymer seal with the bonding surface of the seal attachment portion. And a seal attachment portion operable to provide sealing contact of the fluoropolymer seal along the entirety of the entire sealing face when engaged with the engagement face of the shaft. 30. The radial shaft seal of claim 29, wherein stretching the fluoropolymer seal preform at least relative to the inner diameter comprises stretching the preform in the range of approximately 5-180% of the inner diameter. How to prepare. 30. The method of claim 29, wherein stretching the fluoropolymer seal preform also includes stretching the preform with respect to the outer diameter. 30. The radial shaft of claim 29, wherein stretching the fluoropolymer seal preform at least relative to the inner diameter further comprises sliding the fluoropolymer seal preform along the tapered outer surface of the mandrel device. How to make a seal. 30. The method of claim 29, wherein sliding the fluoropolymer seal preform along the tapered outer surface expands along the tapered surface and maintains contact with either of the sealing and bonding surfaces of the fluoropolymer seal preform. A method of manufacturing a radial shaft seal, characterized in that it is carried out using a possible pusher tool. 30. The method of claim 29, wherein the mandrel device is detachably attached to the mold. 30. The method of claim 29, wherein the mold comprises an integral mandrel device. 30. The method of claim 29, wherein positioning the prestressed fluoropolymer seal having a bonding surface and a sealing surface in a mold comprises positioning the prestressed fluoropolymer seal on a post face of the mold. How to make a shaft seal. 37. The tapered cylindrical surface of claim 36, wherein the post face is a tapered cylindrical face having a first end diameter portion and a second end diameter portion opposite the second end diameter portion, wherein the second end diameter portion is larger than the first end diameter portion. A method of making a radial shaft seal. 37. The method of claim 36, wherein positioning the prestressed fluoropolymer seal comprises placing the prestressed fluoropolymer seal on a post face having an inner diameter near the first end diameter and an outer diameter near the second end diameter. A method of making a radial shaft seal. 41. The method of claim 40, wherein the second end diameter portion is larger than the outer diameter portion of the fluoropolymer seal preform. 41. The method of claim 40, wherein the first end diameter portion is larger than the inner diameter portion of the fluoropolymer seal preform. 41. The method of claim 40, wherein the second end diameter portion is larger than the outer diameter portion of the fluoropolymer seal preform and the first end diameter portion is larger than the inner diameter portion of the fluoropolymer seal preform. 41. The method of claim 40, wherein the second end diameter portion and the first end diameter portion are each larger than the outer diameter portion of the fluoropolymer seal preform. 38. The method of claim 37, wherein positioning the prestressed fluoropolymer seal comprises placing the prestressed fluoropolymer seal on a post face having an inner diameter near the second end diameter and an outer diameter near the first end diameter. A method of making a radial shaft seal. 44. The method of claim 43, wherein the second end diameter portion is larger than the outer diameter portion of the fluoropolymer seal preform. 44. The method of claim 43, wherein the first end diameter portion is larger than the inner diameter portion of the fluoropolymer seal preform. 44. The method of claim 43, wherein the second end diameter portion is larger than the outer diameter portion of the fluoropolymer seal preform and the first end diameter portion is larger than the inner diameter portion of the fluoropolymer seal preform. 44. The method of claim 43, wherein the second end diameter portion and the first end diameter portion are each larger than the outer diameter portion of the fluoropolymer seal preform. 30. The method of claim 29, wherein directing the elastomeric material into the mold cavity comprises injection molding. 49. The method of claim 48, wherein the injection molding of the elastomer is performed at a temperature and pressure greater than ambient temperature and atmospheric pressure. 50. The method of claim 49, further comprising calibrating one or more of a temperature and pressure greater than ambient temperature and atmospheric pressure.

Images